rule approximation, pure dephasing due to BCS quasiparticles gives rise to a divergent golden rule rate. We calculate qubit dephasing due to quasiparticle tunneling beyond lowest order approximation in coupling between qubit and quasiparticles. Summing up a certain class of diagrams we show that qubit dephasing due to purely longitudinal coupling to quasiparticles leads to a dephasing ∼exp(−x(t)) where x(t) is not linear in time on short time scales while it tends towards a selfconsistent calculated dephasing rate for longer times.